The coastal scarps of a water body (such as an ocean, sea, river, lake), a valley or artificial pit become weathered and disintegrate by the effect of wind, rain, contained surface water, water flow and significant alteration between minus and plus degrees of outdoor temperature (incl. disintegration resulting from volumetric expansion of freezing soil and then shrinking of the expanded soil in the course of thawing). In addition, numerous landslips of the scarp soil occur as a result of human activity or earthquakes.
Natural slopes or scarps have predominantly a very complex structure and the quantity and state of surface water contained in the scarp as well as the causes of erosion are dependent on very many factors (such as rainfall, wind, outdoor air temperature, etc.). Whilst these factors and the intensity of their effect change in time. Numerous factors have been determined empirically, wherefore it is necessary to make significantly allowance for high safety margins in solution planning. Therefore the solutions for ensuring the stability of a scarps, for example, when building a retaining wall, should also account for various climatic, geological and hydrogeological conditions and thus these solutions are by nature very elaborate, resource-intense, multifaceted and diverse.
Well-known methods of scarps reinforcement include facilities from artificial materials, such as retaining walls of steel, stone, reinforced concrete and composite materials, or stabilization of soil by means of hardening compounds and reinforcement with geo-materials. These solutions change the natural environment on a major scale, have high substantially costs, are resource-intense and also in addition to creating the systems for draining the rainwater and surface from the soil require the application of measures for soil hardening.
These well-known solutions are noted below:
Noted solution (WO9839518, Eardley D. J, Martin B, published Nov. 9, 1998), where for the purpose of reinforcement a base frame is installed at the bottom of the body of water. A ballast supporting member is fixed to the base frame, and ballast, such as rocks, can be mounted to the frame, and the frame can be anchored in position. A barrier wall is fixed to the frame.
Noted solution (TW1262974, Lee Der-Her, Yang Yi-En, published Jan. 10, 2006) for slope protection, with the following structure: filter layers, metal frames, soil with vegetation, a retaining wall and drains. The slope is excavated to form steps, platforms and transverse drains in the slope. Drains and platforms are laid at the foot of each step in the slope. The fastening elements of the metal frames are positioned on the retaining wall, platform and drains. The vertical elements of the metal frame are assembled to form vertical units of the metal frame along the slope. The transverse elements of metal frames are assembled to cover the slope. Vegetation soils and vegetation belts are laid on the metal frame, the plants grow through the metal frame and protect the slope against erosion.
Noted solution (EP0174253, France Etat, Mur Ebal Sarl, published Dec. 3, 1986), which uses the covering of a bank with compacted soil, while the mass of earth is reinforced with plates of geotextile. The facing for the bank is formed of plates that are individually hooked to the bank by means of flexible elements. The plates are installed mainly in horizontal rows, while the plates of one row partially overlap the plates of the row immediately beneath.
Noted solution (EP0603460, RDB Plastotecnica SPA, published Jun. 29, 1994), which uses an internally reinforced geotechnical structure with an exposed surface, suitable for the formation of slopes, walls and systems for the prevention of erosion. The structure comprises of several layers, which are superimposed and have their exposed surface either in a vertical or tapered form aligned from the base to the top. Each layer consist of at least one primary reinforcement and a separation element, which is arranged so that the primary segment lies along the horizontal plane: Then it is folded onto itself, the folded segment continues with a second segment in order to contain at least one portion of material. Outwards by the folded segment, i.e. towards the first segment, each layer has a second reinforcement element that preferably consists of a containment frame for containing the bulk material, which covers the first reinforcement layer.
The most technically similar to the presented one is the method for slope reinforcement by means of geosynthetic materials (US2007041793, MEGA, INC, published Feb. 22, 2007). The presented solution contains the following stages: preparation of the soil remaining under the reinforcement; containers made from geosynthetic material are placed on the prepared surface; the containers are filled with fine-grained material; then the reinforcement structure is erected and at least one structure is reinforced for supporting the container structure; the material for covering the surface of the structure and the fill material of containers is selected; the area behind the containers is filled with soil and a drain layer and water guiding pipelines are installed in the slope prior to the installation of containers.
These noted solutions, however, fail to provide scarps with sufficient stability against extreme as well as normal exposure factors occurring over time. Protection is needed for the slopes of soil or scarps against freeze-thaw effects and against various impacts of erosion, waves of water bodies, flow of water, ice, earthquakes or human activity. The systems for draining surface water from behind the retaining wall and the retaining walls themselves require maintenance, repair, and are destroyed in earthquakes due to dislocation resulting from compaction of scarp soil or substantial or abrupt changes in the state and volume of the surface water in the scarp. Retaining walls that are produced from soil stabilised with cement or oil-shale ash, or from fine-grained (i.e. non-drain or low-drain) soil also require drainage pipelines.